The present invention pertains to a switching process and to a new type of slide control valve designed for the control of a hydraulic circuit of the same type as those used on machines, vehicles, public work equipment, or mining equipment.
This type of hydraulic circuit is usually operated by means of a control valve having a spool sliding longitudinally inside the bore of a stator. Grooves are provided on the surface of the spool which moves in front of ports opening into the bore. Each one of the ports is connected with one conduit of the circuit. Therefore, the consecutive areas of the spool's periphery cover or uncover the side openings of the bore.
Generally, this arrangement is quite satisfactory, but the apparatus is not entirely sealed and, therefore, cannot be used with aqueous fluids as leaks become too important. In order to obtain a satisfactory internal watertightness, the spool must be equipped with gaskets which slide when passing in front of the openings located on the periphery of the bore. Experience shows that if great care is not exercised during assembly operations, the gaskets deteriorate quickly as they are repeatedly passed in front of the bore openings. It has been found that the higher the pressures to which the gaskets are subjected, the more rapid their deterioration.
The present invention eliminates these disadvantages by offering a watertight slide control valve whose gaskets are able to repeatedly pass in front of the bore openings without deteriorating.